<html>
<body>
<p>Here is a simple matrix</p>
<math>
<mtable>
<mtr>
<mtd> <mn>4</mn> </mtd>
<mtd> <mi>x</mi> </mtd>
</mtr>
<mtr>
<mtd><mi>400</mi></mtd>
<mtd><mi>x</mi><mi>y</mi></mtd>
</mtr>
</mtable>
</math>
<p>It has two rows and two columns.</p>
</body>
</html>
